1. Technical Field
The present invention relates liquid crystal displays, and more particularly, to a panel driving circuit that generates pattern test data and pattern test signals for testing a panel, and a method of testing the panel using the panel driving circuit.
2. Description of the Related Art
FIG. 1 is a block diagram of a conventional liquid crystal display (LCD) panel driving system. Referring to FIG. 1, the conventional LCD panel driving system 100 includes a driving circuit 120, a graphic processor 130, a memory 140, a Central Processing Unit (CPU) 150, and peripheral circuits 160 and 170. The CPU 150 applies a control signal S_COM to the graphic processor 130 to control the panel 110 and the driving circuit 120. The memory 140 applies data DATA to the graphic processor 130. In response to the control signal S_COM outputted from the CPU 150 and the data DATA outputted from the memory 140, the graphic processor 130 applies a horizontal synchronizing signal HSYNC, a vertical synchronizing signal VSYNC, the data DATA, a system clock DCLK, and any of a variety of other inputs to the driving circuit 120 to drive the panel 110.
In response to the horizontal synchronizing signal HSYNC, the vertical synchronizing signal VSYNC, the data DATA, and the system clock DCLK inputted to the driving circuit 120, the driving circuit 120 produces a gate line control signal S_GATE and a source line control signal S_SOURCE that control a gate line (not shown) and a source line (not shown) of the panel 110, respectively. When the gate line of the panel 110 is turned on by the gate line control signal S_GATE, the data DATA is applied to the panel 110 through the source control signal S_SOURCE.
There are two operation modes of the driving circuit 120. One is a CPU interface mode in which the driving circuit 120 interfaces directly with the CPU 150 and receives the control signal S_COM from the CPU 150 directly (not shown in FIG. 1). The other, a shown in FIG. 1, is a video interface mode in which the graphic processor 130 exists between the driving circuit 120 and the CPU 150 and the driving circuit 120 interfaces directly with the graphic processor 130. A driving circuit that operates in the video interface mode is widely used in display devices of mobile communications devices like mobile phones.
An alternate version of the driving circuit 120 has fewer circuits that the CPU 150 controls and reduces the burden on the CPU 150. As a result, the alternate version of the driving circuit 120 usually adapts the video interface mode that interfaces directly with the graphic processor 130 Further, the alternate version of the driving circuit 120 can embody various image functions as well as eliminate problems, such as low image quality. Low image quality may result from a tearing condition which can occur in the CPU interface mode while reproducing a moving image. The driving circuit 120 of FIG. 1 shows the driving circuit 120 operating in the video interface mode, in which the driving circuit 120 interfaces directly with the graphic processor 130. However, the driving circuit 120 of FIG. 1 carries out a test on the panel 110 such as an image test, a reliance test, and the like, by receiving signals needed from a separate external testing device.
FIG. 2 is a conventional method of testing a panel using the driving circuit of FIG. 1. Referring to FIG. 2, a driving circuit 220 receives signals needed to test a panel 210 from an external testing device 230.
When testing the panel 210, a test pattern S_PATTERN such as gray, cross-talk, and flicker patterns are applied to the panel 210 to check whether the panel 210 displays the test pattern S_PATTERN correctly. The driving circuit 220 receives a vertical synchronizing signal VSYNC, a horizontal synchronizing signal HSYNC, a system clock DCLK, a data activating signal DE, and data DATA and generates the test pattern S_PATTERN and applies the test pattern S_PATTERN to the panel 210.
Thus, the testing of the panel 210 using the conventional driving circuit 220 becomes more complex. The conventional driving circuit 220 receives signals for generating the test pattern S_PATTERN from the external testing device 230. As a result, the conventional driving circuit 220 must consider the conditions of the external testing device 230 and the interface between the conventional driving circuit 220 and the external testing device 230.